The invention relates to a method of and an apparatus for measuring surface temperature of linearly moving and/or rotating objects, and advantageously for measuring the temperature of fibrous products, particularly of wire during production. In the method according to the invention a measuring head is fitted to the object to be measured. The method and apparatus according to the invention are suitable for measuring surface temperature of moving objects at a high accuracy, and it allows an accurate measurement of the surface temperature particularly in the wire production, in a wide speed range of the wire transfer (up to the speed of 65 m/s).
Fibrous products produced in high volume, among them wires, are usually produced by technologies with continuous issue. The quality of the products is considerably influenced by the temperature during production, which has to be kept for this very reason at a constant value. The same task can also be met e.g. in case of a rotary furnace equipment, i.e. in case of large dimensions, when accurate knowledge of the surface temperature is also required. The diameter and/or thickness, the speed of movement (rotation) of the products (and of the object to be measured) can vary in a wide range of values. Temperature can be kept within the designated range only if the apparatus measuring the temperature is able to follow the varying parameters with proper flexibility and it affords accurate measurement even under varying conditions.
Two basic types of used for measuring surface temperature of moving (rotating) objects are the temperature measuring means which contact and those which do not contact the object to be measured.
By the temperature measuring means being contiguous with the object to be measured a relatively high accuracy can be achieved in case of non-moving objects. If, however, a heat receiving element is in contact with the surface of moving objects, and consequently moving elements are employed in them, their accuracy is low. In many cases accuracy is even smaller than 25 percent. The abrasive effect of the moving surface can be considerable, particularly in wire production.
The apparatus of type NCT-4500 (with WIRETEMP trade mark) was developed for measuring surface temperature of moving wires or fibres. Its essence lies in that the object to be measured is strained on a proper element of the apparatus, then the object to be measured is calibrated before starting the measurement, depending on the diameter, quality of material, speed of the object and the expected temperature range. This renders the apparatus uncomfortable to manipulate.
The known basic principles of the non-contacting measurement of temperature are based on the measurement of radiation. Their basic problem is that a material of extremely uneven surface, and accordingly, of varying emission factor is to be measured, and these changes can not be foreseen. Consequently the result of measurement is burdened with considerable error. The result is also strongly influenced by cleaness of the medium of measurement.